Presently, different instruments exist which use a light (laser) ray to project on a surface. The power light source or laser can be generally used in order to produce the light line. It is known, that the diode-lasers are mostly used as sources of illumination in various graphics applications. For such applications some optical instruments have been devised to optically shape the characteristic astigmatic light output of a diode-laser into a symmetrical anastigmatic form that can be focussed into an biaxially symmetrical spot or illuminating area. For instance, a very small, uniform spot of light projected from a diode-laser can be used to record correspondingly small spots on a light sensitive medium. A plurality of small spots recorded over an area can be used to record a graphic image or pattern. A line of small light dots can form a light line also, but more efficient use of the laser diode (a.k.a. the diode-laser), when the laser diode light could be projected into the form of a fine narrow line.
For example, the U.S. Pat. No. 6,478,452 describes the illumination apparatus for projecting the light-output of a semiconductor-laser into a fine line. The light-output propagates in a direction mutually perpendicular to the first and second axes. The optical system is arranged cooperative with the semiconductor-laser to focus the light-output in the first and second axes at respectively first and second focal points spaced apart in the propagation direction. At a plane intersecting the first focal point perpendicular to the direction of propagation, the focused semiconductor-laser light-output is formed into a line of light having a width in the first axis and a length in the second axis. The first focal point is closer to the optical system than the second focal point. The semiconductor laser emitting light-output has a different divergence in characteristic fast and slow axes. The fast and slow axes correspond to above discussed first and second axes respectively. The system uses the manufactured laser diode (e.g. such as the laser diode by “Hitachi Co.”, “Sony”, etc.). The system includes first, second and third lenses spaced apart in consecutive numerical order in the direction of propagation. The first and third lenses each has a positive dioptric power in both the first and second axes. The second lens has zero dioptric power in the first axis and positive dioptric power in the second axis. The first lens is spaced apart from the semiconductor laser by a distance equal to about its focal length. The second lens is spaced apart from the third lens by a distance greater than the second-axis focal length. The third lens has a focal length greater than the focal length of the first lens, and the second lens has a second-axis focal length greater than the focal length of the third lens. The first focal point is closer to the optical system than the second focal point.
The first convex—convex lens is located at a distance about equal to its effective focal length from diode-laser and collimates beam in both the fast and slow axes considering that the astigmatism of beam is not corrected by the first lens. The second plano-convex cylindrical lens, in the slow axis brings the collimated beam to an intermediate focus between itself and third lens, while in the fast axis the beam remains collimated. The third convex—convex lens receives a diverging beam in the slow axis and a collimated beam in the fast axis. Accordingly, light in the fast axis is brought to a sharp focus and light in the slow axis is brought to another focus further removed from exit face of the third lens. A result of this is that in an X-Y plane at one of the focuses there is a line of light having a width in the fast axis defined by the fast axis focal-spot size and a length in the slow axis defined by the beam width in the slow axis at the defined distance from exit-face of the third lens. The ratio between the beam width in the slow axis and the focal-spot size in the fast axis can be at rank from 20:1 to 50:1.
While this known system produces the light line, it is complex, comprises at least three lenses requiring precise focusing.
Another U.S. Pat. No. 6,494,371 presents the diode-laser light projector also producing a liner array. The optical system in this invention is arranged to focus the fast-axis diverging rays in a focal plane perpendicular to the longitudinal optical axis, and arranged to form the slow-axis diverging rays into a plurality of bundles of parallel rays, one thereof for each diode-laser. The bundles of parallel rays intersect in the focal plane. The optical system causes light from the diode-lasers to be formed into a line of light in the focal plane. The line of light has a width in the fast axis and a length in the slow axis. the emitting apertures of the diode-laser bars are located in a slow-axis object plane of the optical system and the bundles of parallel rays intersect in a slow-axis exit-pupil of the optical system. Fast axis rays are focussed in the slow-axis exit-pupil thereby providing the line of light. The line of light has a width equal to about the fast-axis focal spot-size and a length about equal to the width of the slow-axis exit-pupil. Considering the first variant of invention, the optical system does not include any microlens arrays wherein individual optical elements operate on rays from corresponding individual diode-lasers. In the inventive optical system, rays from all diode-lasers traverse all optical elements of the optical system. In another aspect of the mentioned prior art, the optical system may include one or more physical stops arranged to prevent selected portions the fast and slow-axis diverging rays from the diode-laser array from reaching the fast-axis focal plane. The selected portions are chosen to optimize the intensity of light distribution along the length of the line of light, and each of the physical stops is an elongated stop formed from a length of optical fiber having a length extending completely through the fast-axis rays from the diode-laser array. The projector includes the line projector comprising a light-source a diode-laser bar. Diode laser bar is in thermal contact with a heat-sink. Diode-laser bar also includes a plurality of diode-lasers, each thereof having an emitting aperture. The diode laser bar can be defined as having a fill-factor which is the percentage of the total length of the bar occupied by diode-lasers and is dependent on the width of the diode-lasers and spacing between diode lasers. The diode-laser bar (and diode-lasers therein) is also characterized by a slow axis X parallel to the width direction of emitting apertures, and a fast axis Y perpendicular to slow axis X. Light is emitted from an emitting aperture in a general direction (axis) of propagation Z mutually perpendicular to the fast and slow axes. The light is emitted in the form of a diverging beam. Rays of beam in fast axis Y diverge at an included angle of about 32°. Rays of beam in the slow axis X diverge at an included angle of about 7.5°. Additionally the line-projector includes an (anamorphic) optical system which has a different optical prescription in the fast axis Y and slow axis X. Optical system can be defined as having a longitudinal axis aligned parallel to the general direction of propagation (Z axis) of light from beams. Optical system includes two lenses. The first lens has positive optical (dioptric) power in fast axis Y but has zero optical power in slow axis X, and the second lens has positive optical power in both the fast and slow axes.
Also, the optical system comprises an object plane located at a first distance from the first lens equal to about the effective focal length, and at a second distance from the second lens about equal to an effective focal length. Both distances are specified in each case from a principal plane of the lens. Emitting apertures of diode-laser bar are aligned about in object plane of optical system. The relative placement of the first lens and emitting apertures causes rays leaving the emitting apertures in the fast axis to be collimated. The collimated fast axis rays are thus incident on the second lens, which focuses the fast-axis collimated rays into a focal plane about one effective focal length of the this second lens. Considering, that the first lens has zero optical power in the slow axis, rays leaving emitting-apertures continue through the first lens maintaining their original divergence as they are incident on second lens. Diverging sets or bundles (three) of slow-axis rays are formed by second lens into corresponding parallel sets of slow-axis rays, which from the central emitting-aperture are parallel to axis of optical system. The sets of these rays intersect in fast axis focal-plane. The intersection of rays is defined as occurring at a slow-axis pupil of optical system. The result of this is that a line of light is formed about in fast-axis focal plane. The described optical system includes a plurality of diode-lasers forming a diode-laser bar, and contributing about equally to form light line.
This projector is a complex, comprises at least two lenses (or combination of the single lenses) requiring precise focusing. Additionally, the failure of some diode-lasers significantly reduce intensity with a significant change in light distribution along the line, thereby forming some kind of dash-line instead of the uninterrupted line.
Slightly more efficient and less complex laser line creating device is described in the U.S. Pat. No. 6,735,879. This device is more directly intended for alignment of surfaces. As known, he alignment of the surface is a perennial problem in a variety of fields, ranging from construction to interior decorating. Alignment is necessary for walls that should be perpendicular to a floor. Masonry and brick-laying practitioners are well aware of the importance of plumbed and aligned surfaces and chalk lines. A home interior decorated with pictures and other wall ornamentation makes a much better appearance when the ornamentation is precisely aligned, especially with respect to vertical or horizontal axes. The conventional laser is not well-equipped for projecting a flat or planar beam of light. The essence of laser light is that it is coherent or substantially monochromatic, that is, of a single wavelength or a narrow wavelength band. It is known, that when a beam of laser light is refracted through a prism, the prism output is not a spreading of the beam as with ordinary “white” light, but rather a coherent, focused beam, very similar. The laser beam is thin and is usefully only visible when projected onto a surface. The device includes a generator and a housing having a handgrip means for handling. The generator has a first leveling device, a spirit level or “bubble” for orientation or leveling in one plane, such as horizontal or vertical. It also has a second leveling device, for orientation or leveling in a second plane perpendicular to the first plane. The housing contains a protective door with a linked switch for turning on the laser light source when opening the door for access to the laser beam. The generator also comprises the retractable pins permanently installed in the housing and raised so that the pin remains inside the housing (inside the device), collimation optics including at least one collimating lens, a projection lens, the door (aperture) providing a passage for the generated light. The housing includes the holes providing passage of the retractable pins. The light is collimated into an ovate shape by collimation optics, comprising the collimating lens(es), by techniques well known to those skilled in optic arts. The ovate beam then enters a projection lens.
This device does not provide the surface lining under different angles to the longitudinal and lateral axes (for example, under 34°).
Other known devices, such as manual leveling rotating laser with swivel head by U.S. Design Pat. No. D470,423 and instrument for obtaining a reference line by U.S. Pat. No. 6,493,955 provide some possibility to changeability of the illuminated line angle.
But, for instance, the manual leveling rotating laser with swivel head (U.S. D470,423) does not provide precise evaluation of the angle (the position of the device head is not accurate determined, e.g. it is not exactly known is the head rotated to 35° or 38° angle, etc.).
The mentioned above instrument for obtaining a reference line by (U.S. Pat. No. 6,493,955) includes the aluminum bar, which is the supporting body of the laser emitting device, two water levels mounted on the supporting body. The water levels provide the perpendicularity or parallelism with respect to the ground of the ray of light emitted from the laser diode. Also, the instrument comprises the hinge ball. The laser device is mounted on the supporting body (by a two-component resin). The device comprises also a lens, which focuses the laser ray emitted by the laser diode.
The instrument also has a cavity located in the center of the body. This cavity is intended for the ball enables the connecting of the supporting body of the device emitting the ray of light to a wall. The hingedly connecting ball is inserted in the cavity of the supporting body in respect of which it is mobile with friction, due to the fact that it is held in a cavity of the supporting body by two bushes or washers in nylon opposite each other. The bushes or washers are fixed to the supporting body of the instrument by the connecting screws.
This rotating laser has limited utility considering the same deficiency mentioned above, i.e. it does not provide precise evaluation of the angle (the position of the device head is not accurate determined, e.g. it is not exactly known is the head rotated to 35° or 38° angle, etc.).
Most known construction, mechanical and/or electrical alignment devices are cumbersome, some of them are not as useful as they could be, for instance, the use of the chalk lining devices is sometimes undesirable and/or inapplicable for the finished, interior areas.
Thus, there is a great need in the art for the improved not complex and not expensive apparatus generating light illuminated line, providing a precise angles of the light line relatively to the horizontal and/or vertical axes on the reference surface (e.g. construction wall, etc.).